The present invention relates to optical connectors and, more particularly, to self-aligning optical connectors.
Fiber-optic data networks include cables through which data signals are transmitted. The cables usually include glass and transmit light signals. Adjacent fiber-optic cables in these networks are joined by connectors and must be accurately aligned to ensure the data signals properly propagate from cable to cable. Thus, the connectors must hold the cables from becoming misaligned. Keeping adjacent cables aligned is especially difficult under severe conditions. For example, aerospace applications may expose networks to vibration, contamination, and extreme temperatures. Such conditions often result in cable misalignment when conventional connectors are used. Detachment and reconnection of conventional connectors, such as during cable replacement or connector maintenance, can also lower the ability of the connectors to hold adjacent cables within desired tolerance levels.
Some fiber-optic networks require very tight tolerance connectors to ensure data signals are properly transmitted through the connectors. For example, single-mode fiber-optic networks generally require tighter tolerance connections than multimode fiber-optic networks. Fiber-optic cables generally include a cladding surrounding a central core through which data signals are transmitted. In single-mode fiber-optic networks, a single high-strength signal is transmitted generally down the center of the core. In multimode fiber-optic networks, multiple signals are simultaneously transmitted through the core.
Although some or most of the signals transmitted through the cable in a multimode network may travel along a center of the core, at least some of the signals will propagate along paths other than directly down the center. Claddings are generally made of a material having a lower index of refraction than that of the core so that signals propagating toward the cladding are refracted or bent away from the cladding. Off-center signals are refracted back and forth as they move along the cable. Multimode networks can operate with looser connection tolerances because many or most of the multiple signals being transmitted through the cables can usually pass through the connector even if some are stopped. Multimode networks produce relatively low quality output data for at least two reasons. A first reason is that because the signals move through the cable along various paths, the signals will invariably arrive at the destination at various times. Thus, the terminating sensor or device must arrange the time-spaced signals together to form the resulting data. A second reason for low quality output in multimode systems is that many of the signals may get impeded at very loose joints between adjacent cables. Therefore, even with multi-mode fiber-optic networks, quality connectors are needed to ensure proper joint alignment.
Data is generally transmitted more accurately through single-mode fiber-optic networks because terminal devices only receive one signal and, thus, do not need to piece together multiple dispersed signals to form the data. However, because only a single signal stream is transmitted, it is imperative that the signals are not impeded as they travel through the network. Accordingly, the cables must be joined together within a very tight tolerance to ensure the signals pass through the joint. Conventional connectors exist that can maintain a relatively tight tolerance connection, but only under gentle conditions. Conventional connectors also exist that can withstand severe conditions, but can only maintain a loose connection. Connectors are needed that can keep fiber-optic cables aligned within very tight tolerances under severe conditions.